Milestone / sprint  

A milestone in The Bug Genie is a period of time (or unspecified period of time) where you're working on issues. You can/may have several milestones without releases (depending on how you work), but you can/may also have a release at the end of each milestone period. The milestone itself represent a point in time where a set of features are completed or bugs are fixed, and this often results in a release. The milestone itself, however, is a way of grouping bugs, features and issues into a set that will be fixed / implemented at a specific (or unspecified) point in time.

Release  

The release is the package that gets released to customers / users to download / install and use. This may be a specific release linked to a milestone, or it may be a standalone release that is not linked to a milestone. Usually, a release is linked to a milestone and this link makes it easy to see what has been changed since the previous release.

You don't discover issues in a release, and an issue may be present in several releases. This way, you can add each affected release to a bug report, and keep assigning it to a milestone until it is actually fixed in that milestone. When the issue is fixed, you can add the fixed release to the issue and mark it as fixed in that release (each affected release has a status). The milestone link in the issue tells you during which milestone the issue was fixed.

You may use the same naming for your milestones and releases (we do), such as "Release 1.1" and "Release 1.2", but where the release (in TBG) is the actual released software, the milestone (in TBG) is "the period of time we worked, culminating in the release of 1.2".

Keep in mind that this is how we intended this to work. Your process may be different, and it may not map at all to this. We do our best to make TBG fit your process, so most of this is customizable. If you think or feel it is too complicated to distinguish between milestones and releases, just make a custom issue type scheme and disable one of them or change settings for them.